A compact disk appendix is included containing computer program code listings pursuant to 37 C.F.R. 1.52(e) and is hereby incorporated by reference. The compact disk contains program code files in ASCII format. The total number of compact disks is 1 and the files included on the compact disk are as follows:
The present invention relates to systems and components for the protection, control, and/or energy management of electricity distribution systems for electric utility industrial, manufacturing, commercial, and/or institutional use.
Monitoring of electric parameters, such as current, voltage, energy, power, etc., particularly the measuring and calculating of electric parameters, provides valuable information for power utilities and their customers. Monitoring of electric power is important to ensure that the electric power is effectively and efficiently generated, distributed and utilized. Knowledge about power parameters such as volts, amps, watts, phase relationship between waveforms, KWH, KVAR, KVARB, KVA, KVAH, power factor, frequency, etc., is of foremost concern for utilities and industrial power users. In addition monitoring of electricity can be used for control and protection purposes.
Typically, electricity from a utility is fed from a primary substation over a distribution cable to several local substations. At the substations, the supply is transformed by distribution transformers from a relatively high voltage on the distributor cable to a lower voltage at which it is supplied to the end consumer. From the substations, the power is provided to industrial users over a distributed power network that supplies power to various loads. Such loads may include, for example, various power machines.
In such arrangements, utilities need to measure power coming out of or into the generating station or going into a power station. It is important to minimize the phase relationship between the current and voltage waveforms of the power being transmitted to minimize losses. It is also important to minimize the amount of harmonics that are present in the voltage and current waveforms. Also, the ability to detect the presence and magnitude of faults in the power system is important. Thus, accurate measurement of these waveforms is important.
In industrial applications, it is important to continuously monitor the voltage, current, phase, harmonics, faults and three phase balance of the power into the machine. These parameters may vary with the machine load. With knowledge of these parameters, the industrial user can better adjust and manage the loads to control machines, determine alarm conditions and/or more efficiently use the power.
Many protection, control, and metering functions in a modern power distribution system require concurrent knowledge of the states of multiple circuits in the system in order to work efficiently and effectively. Examples include differential protection devices and breaker coordination schemes, Conventional devices and systems have addressed these requirements by various coordination and data sharing arrangements. Many of these approaches suffer from cost, performance, reliability, security, and scalability problems.
Accordingly, it is an objective of the present invention to provide a system that overcomes the disadvantages of the prior art by providing a monitoring system that can be used for protection control, and/or metering of electricity in a electric distribution system.
To achieve the foregoing and other objectives, there is provided an improved phasor monitoring system and apparatus for use with a distribution system for electricity wherein periodic three phase electricity is distributed in a plurality of circuits. The phasor monitoring apparatus comprises a phasor transducer that has an input that receives analog signals representative of parameters of electricity in a circuit of the distribution system. The phasor transducer also includes an analog to digital converter that receives the analog signals and that outputs a digital data signal representative of the analog signals and a processor coupled to the analog to digital converter to receive the digital data signal output therefrom. Programming on the processor of the phasor transducer computes phasor data representative of the electricity in the circuit based on the digital data received from the analog to digital converter and provides a digital output representative of the phasor data. The phasor transducer also includes a network-compatible port coupled to the processor to transmit the phasor data onto a digital data network.
According to a further aspect, there is provided a phasor monitoring system for use with an electricity distribution system having a plurality of circuits. The phasor monitoring system comprises a data network interconnecting a plurality of phasor transducers. Each phasor transducer is associated with one of the circuits of the electricity distribution system. One or more phasor array processors are connected to the data network to receive phasor data from the plurality of phasor transducers connected to the network. The phasor array processor computes combined phasor data for the plurality of circuits in the electricity distribution system based upon the phasor data received from the plurality of phasor transducers.
According to a further aspect, associated with each of the circuits of the electricity distribution system is a protection device. The protection device is coupled to the data network. Each of the protection devices is also connected to a circuit breaker associated with one of the circuits. The protection device operates its respective circuit breaker based upon data instructions received over the data network.